Financing (Details) (USD $) In Millions	Sep. 30, 2011
Credit arrangements by company
Total	$ 5,132
Unused	5,127
Executable Term-Loans, One Year	216
Executable Term-Loans, Two Years	41
Expires, 2011	96
Expires, 2012	316
Expires, 2013 and Beyond	4,720
Expires Within One Year, Term Out	257
Expires Within One Year, No Term Out	156
Southern Company [Member]
Credit arrangements by company
Total	1,000
Unused	1,000
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Expires, 2011	0
Expires, 2012	0
Expires, 2013 and Beyond	1,000
Expires Within One Year, Term Out	0
Expires Within One Year, No Term Out	0
Alabama Power [Member]
Credit arrangements by company
Total	1,296
Unused	1,296
Executable Term-Loans, One Year	111
Executable Term-Loans, Two Years	0
Expires, 2011	60
Expires, 2012	121
Expires, 2013 and Beyond	1,115
Expires Within One Year, Term Out	111
Expires Within One Year, No Term Out	71
Georgia Power [Member]
Credit arrangements by company
Total	1,750
Unused	1,745
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Expires, 2011	0
Expires, 2012	0
Expires, 2013 and Beyond	1,750
Expires Within One Year, Term Out	0
Expires Within One Year, No Term Out	0
Gulf Power [Member]
Credit arrangements by company
Total	240
Unused	240
Executable Term-Loans, One Year	55
Executable Term-Loans, Two Years	0
Expires, 2011	20
Expires, 2012	55
Expires, 2013 and Beyond	165
Expires Within One Year, Term Out	55
Expires Within One Year, No Term Out	20
Mississippi Power [Member]
Credit arrangements by company
Total	296
Unused	296
Executable Term-Loans, One Year	25
Executable Term-Loans, Two Years	41
Expires, 2011	16
Expires, 2012	115
Expires, 2013 and Beyond	165
Expires Within One Year, Term Out	66
Expires Within One Year, No Term Out	65
Southern Power [Member]
Credit arrangements by company
Total	500
Unused	500
Executable Term-Loans, One Year	0
Executable Term-Loans, Two Years	0
Expires, 2011	0
Expires, 2012	0
Expires, 2013 and Beyond	500
Expires Within One Year, Term Out	0
Expires Within One Year, No Term Out	0
Other Subsidiaries [Member]
Credit arrangements by company
Total	50
Unused	50
Executable Term-Loans, One Year	25
Executable Term-Loans, Two Years	0
Expires, 2011	0
Expires, 2012	25
Expires, 2013 and Beyond	25
Expires Within One Year, Term Out	25
Expires Within One Year, No Term Out	$ 0

Bank credit arrangements no term loan option expires with in one year.

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Namespace Prefix:	so
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Bank credit arrangements term loan option expires with in one year.

+ Details

Name:	so_BankCreditArrangementsTermLoanOptionExpiresWithInOneYear
Namespace Prefix:	so
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Executable term-loans for one year.

+ Details

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Namespace Prefix:	so
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Executable term loans for two years.

+ Details

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Namespace Prefix:	so
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit expire year one.

+ Details

Name:	so_LineOfCreditExpireYearOne
Namespace Prefix:	so
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit expire year three and thereafter.

+ Details

Name:	so_LineOfCreditExpireYearThreeAndThereafter
Namespace Prefix:	so
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit expire year two.

+ Details

Name:	so_LineOfCreditExpireYearTwo
Namespace Prefix:	so
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LineOfCreditFacilityAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant